Automatic telephone system.



A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED JAN. 8, 1909.

Patented May 31, 1910.

5 SHEETS-SHEET 1.

I A. H. DYSON'. AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED JAN. 8,1909.

Patented May 31, 1910.

5 SHEETS-SHEET 2.

A. H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLIPATION FILED JAN. 8, 1909.

Patented May 31, 1910.

5 SHEETS-SHEET 3.

A. H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLIVOATION FILED JALLB, 1909.

959,485. Patented May "31, 1910.

5 SHEETS-SHEET 4,

aw I a Q mm o go I VaT 1 O n o 9 0M ,DL

A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED JAN.8, 1909.

STATES PATENT @FFIQE.

ALFRED H. DYSON, OF CHICAGO, ILLINOIS, ASSIGNOR, 'BY lVIESINEASSIGNMEE'TS, 'lO KELIJOGG SWITCHBOARD & SUPPLY COMPANY, A CORPORATIONOF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented May 31, left).

Application filed January 8, 1909. Serial No. 471,314.

To all whom it may concern:

Be it known that I, ALFRED H. DYsoN, residing in Chicago, Cook county,Illinois, have invented new and useful Improvements in AutomaticTelephone Systems, of which the following is a specification.

My invention .has special reference to telephone systems wherein thelines are divided into groups and a number of line selectors areemployed for each group to select calling lines as soon as they inltiatecalls. In such systems, the line selectors are preferably not constantlyoperating mechanisms and a starting conductor is used common to thelines of a group and its selectors to start an idle lineselector when acall is initiated. v

An object of the present invention is to provide improved means forcontrolling the starting circuit. It will be seen that the startingmeans is a very important element in such systems, since it is common toa group oflines and all the lines must rely upon it. If such a startingconductor should for some reason he placed out of service, no calls fromthe line group which it serves could be successfully made until thetrouble was ascertained and the starting circuit again put in service.By the present invention, a plurality of starting circuits are providedwith mechanism such that, should one circuit be disabled, another willautomatically, or without the aid of an attendant, be

connected into operative relation with the lines and the line selectors.

Another object of the invention is to provide means in an automatictelephone system, employing line selectors to" select call- 1 in lines,whereby it may be rendered feasib e, when at the conclusion ofconversation --.the subscriber replaceshis receiver, to release all theselectors employed in the connection. In telephone systems Whereautomatic mechanism is employed to inter changeably associate firstselectors with calling lines by the removals of'the receivers at callingsubstations, if one subscriber were to release all selectors byreplacing his receiver, while the other subscriber, for example, forgotto replace his .receiver, the

result would be, were not special means provided to prevent it, that theline, whose receiver was left off the hook, would be automaticallyconnected with a first selector and such first selector wouldaccordingly be unavailable for further-use until the receiver wasreplaced at the connected line. By the present invention, means areprovided to prevent the re-connection of a line, at whose substation thereceiver is left removed, and consequently from beingconnected with afirst selector when all the selectors employed in the connection arerestored. In the present case, this is accomplished by locking thecut-oil relays of the lines over the line circuits, so that, as long asa line circuit remains closed after the cutoff relay has once operated,the normal battery connection to the line will remain open, therebypreventing the switching operations, necessary to con nect a callingline with a first selector, from taking place.

Another object of the inventionis to provide improved meansforpreventing more than one line selector from causing its wipers toenter the group of'contacts containing contacts of a single callingline.

These and other features of the invention will be more specificallyreferred to in the following description of the drawings and will bespecifically pointed out in the appended claims.

In the drawings, Figure 1, consisting of parts -1 to 4, illustrates indiagrammatic form an organization of automatic telephone circuitsarranged to show one practical way 'of putting the present inventioninto service; Figs. 2, 3 and 4 are, respectively, left, front and sideelevations of a selector mechanism adapted for employmentinconnectionwith the circuits of Fig. 1; Fig. 5 is a top view showingadetail of the primary off-normal switch combination of said selector;and Fig. 6 shows a detail of the matic.

primary magnetand the associated-parts of the selector. Figs. 2 to 6inclusive, as well .as Fig. 1, are, to a certain extent, diagram-Referring to be placed in consecutive order from left- 'to right, I-show at C andv C two substat'icns, each associated by line-limbs P, S

. as called lines.

with its individual line circuit D at the exchange; and at M and M Ihave shown duplicate master-switch circuits; at E, the circuits of aline selector; at F, those of a first selector; at H, those of a secondselector; and at K, the circuits of a connector. Assuming a system often thousand subscribers, there would be ten thousand substations like Cand G, each with its line.

The'subscribers, lines may be divided into groups of one hundred, bothas calling and The. called multiple terminals 9, lO'and 11 will appearin the banks of a suitable number of connectors K and are therepreferably arranged in ten sub- I groups often contact sets each,according-to the tens value of the lines; The individual callingmultiple terminals, 51, 52, 53, of one hundred lines are groupedtogether in subgroups of ten contact sets each and are multipled to thebanks of a suitablenumber of line selectors, say, ten, each such lineselector, as E, having wipers 56, 57, 58, adapted for automaticadjustment; when a call is initiated to first selectthe sub-groupinclud-' 'ing the'calling line, and thereafter "the individual terminalsof the calling line out of the sub-group. Each sub-group of ten lineshas a pair of group contacts 54 and 55 which are multipled throughoutthe-line selectors of the'ten-line group.

Each line selector E is, according to the illustrated arrangement,permanently linked to a p'articular'first selector F, so that there willbeas many first selectors as there are line selectors. Each firstselector F has before its wipers 110, 111, 112, a hundred multipledcontact sets 113, 11 1, 115 of second selectors H, which contact setsare arranged in ten groups of ten contact sets each, according to thethousands to which the second selectors are asslgned, all in the usualmanner. A

- first selectorF hasits Wipers first directively adjusted to select agroup of second selectors of the wa'ntedthousand, whereafter the firstselector is automatically operated to pick out the contact set of anidle second selector of the group. Thesecond selectors H have beforetheir wipers 110, 111*. 112,

one hundred multiple contact sets 116, 117,

118, of connectors assigned for connections to the different hundreds ofthe thousand which the, second selector serves. There may be tenconnectors foreach hundred and themultiple contacts 116, 117, 118 of theconnectors for each hundred will form a separate group before the wipersof a secfirst to Fig. 1, whose sheets are 0nd selector. A secondselector is in the usual manner directly adjusted to select the group ofconnector contacts wanted, whereafter the wipers are automaticallyadjusted to select an idle contact set'out of the group.

"Before the wipers 141, 1 12', 143 of a connector K, are multiplecontacts 9, 10, 11,of the one hundred lines which it serves, saidcontacts being grouped according to the tens value of the lines, asbefore indicated. The wlpers of the connector are first primarilyadjusted responsive to directiveimpulsesto ing the set of a called line,and thereafter secondarily adjusted responsive to like impulses toselect the individual contact set of'the called line, all in the usualway.

'Each subscribers line, as C, in addition to the calling andcalledmultiple terminals before referred to, has its line relay LR foroperation when a call is initiated to influence a master-switch M tostart a line se-.

lector, E, to alter the electrical condition of select the sub-group ofcontact sets containthe individual calling multiple terminals 51, 52,53, to render them selectable; .and also to alter the electricalcondition of the group terminals 5 1 to render them selectable. Inaddition, an operated line relay grounds the multiple private calledcontacts 9 of the'line at the connectors to render them busy. Thecut-oil" relay CO includes armature switches to dee'nergize the linerelay and has an energizing Winding 12 energized in response to theselection of the line by a starting impulses are transmitted to the lineselectors. Before the wiper 30, are contacts 31, each connected by awire 43 to a-difl'erout line selector, the wires 43 being employed torender the contact set 28, 31 of a line selector busy atthemaster-switch. Between the contacts 28, are placed the contacts 28connected together and also connected by a W116'29 with the contacts 31before the wiper 30, which contacts 31 are placed between the contacts31. The wipers 27 and 30 are preferably always operated in the samedirection of rotation, no restoring the usual armature-actuated pawl to"mechanism being necessary, and in practice the contacts 28, 28", mayform a circle about the axis of rotation of wiper 37, while contacts'31, 31 also form a circle-about the axis of rotation of the wiper 30.The mastor-switch relay 26, when energized, grounds the wiper 27 tostart a line selector and said relay 26 is common to the one hundredlines of the calling line group, being so rendered by the commonconductor 25 having one hundred branches, one to each line relay of suchline group.

Referring to the group relay 23 controll g by its armature theselectable condition Jf the group contacts 54, each relay 23 of asub-group of ten lines is common to the subgroup, being so rendered by aconductor 24 having ten branches, one to each line re-. lay of itssub-group.

The remaining circuit connections Will be best understood from thefollowing description of operation, wherein itis assumed that the line Cis to be connected for conversation with the line C, whose number may beassumed to be 2845, it being assumed that at the time substation Cinitiates the call, the

apparatus is in the normal condition-that illustrated in- Fig. 1.Subscriber C removes his receiver, whereupon hook-lever 1 engages itsupper contacts and closes a circuit ofbattery-B over' the calling line,extending through normal contact 22, limb S, contact 4, the magnetimpedance 2, the transmitter, returning through contact '3, limb P,normal contact 19, line relay LR, to ground. Armature 15 is thenattracted to ground the called contacts 9 at the connectors, renderingthem busy. Armature 17 disconnects ground from multipled privatecontacts 51 of the line selectors and energizes the group relay 23 whosearmature removes ground from wire 49 and so from the group contacts 54at the line selectors, rendering them selectable. By armature 16, relayLR is disconnected from the line and locks in series with the leftwinding of masterswitch relay 26, the circuit being traced throughheat-coil h, normal contact 35 to battery. The attracted armature ofrelay 26 grounds the starting Wiper 27 of masterswitch -M, circuit beingtraced through the engaged contact 28, wire 44, normal contact 64,primary relay PR, to battery B Relay PR energizes and its armaturecompletes a circuit for alternating current traversing the winding ofmagnet PM, whose resulting actuations drive wipers 56 to 60, inclusive,in a primary direction, each actuation bringing'the wipers 56, 57, 58below a different group of contacts 51, 52,

58., and wipers 59, 60 to engage a successive set of contacts 54., 55.On the first primary step, the P0 contacts are shifted to theiralternate positions, the shifting ofcontact. 64 opening the initialenergizing circuit of relay PR, so that thereafter said relay dependsfor its continued energiz ation upon a circuit extending throughattracted arma ture 66, through group wiper-59, and to grounds oversuccessively engaged group.

contacts 54 of non-calling sub-groups. Relay PR will accordingly remainenergized and magnet PM will receive successive actuations as wiper 59is stepped along, until .said wiper engages the group contact 54 of thesub-group containing the calling line, at.

ternately energized and deenergized, step ping the wipers 56, 57, 58, ina secondary direction to engage successive contact sets 51, 52," 53 oflines of the selected sub-group, the wipers 59, 60 at this timeremaining stationary. initial energizing circuit of relay I opened atcontact 74, because of the-shifting from normal of the secondaryoil-normal, SO, switch contacts on the first secondary etc of the lineselector. thereafter depends for energizing current upon a circuitextending through its at- On the first secondary stegkthe 1s' Thus therelay?!v tracted armature 78, through contact 67, to

wiper 56 and to grounds at successively engaged individual privatemultiplecontacts 51of non-calling lines of the selected subgroup-- Assoon as wiper 56 engages the contact 51 of the calling line, suchcontact will be ungrounded, because the line relay of such line isoperated. Relay deenergizes and its retracted armature .79 opens theenergizing circuit of secondary magnet SM so that said magnet remainsinert, the wipers 56, 57, 58 accordingly resting engaging the contactset 51, 52, '53 of the calling line.

As soon as the relay SR first operated, its

armaturcs 76 and 81 bridged the wires 84 and 85 so that the relays PRand SR at F energized. When relay SR deenergized,.the' relay PR, becauseof the make-before-break arrangement at 76, had a substitute circuitcompleted from battery A over wire 84, contact 57 52,-normal contact at20, winding 12, to battery B. Relay CO accordingly energizes and, by itsarmature 19, extends the circuit of relay PR over limb P,

' through contact 3, upper contacts at l, magnet 2, contact 4, limb S,wire 48, contact 53-.

58, and wire 85 through relaySP/ to battery These shiftin-gs in thecircuit of relay B PR occur without its armatures retractin Theattraction of arm'atureQO of relay C locks the relay to'ground throughwire' 46,

contact 51'56, and contacts 67 and 78. The

opening of contact 21 deenergizes relay LR and the left winding of relay26. On the retraction of armature 15, the grounded armature-2O isconnected to multiple contacts .9 at the connectors continuing thecalling line busy. The private contacts 51 of the calling line at theline selectors are rendered unselect-able, as soon as theline isselected, by the ground at armature 78, and so contlnue while theconnection exlsts.

Returning now to the starting of the line selector E, the shifting ofprimary ofi-normal contact 63 on the first step closed a circuit fromground. at 68, through normal contactv75, resistance r (the commonwire45 having tenbranches, oneto each line selector served by master-switchM) and through the right winding of relay 26 to battery throughheat-coil h. .The windings of relay 26 are opposed and the resistancesof relay LR and o r are so proportioned that the core of relay 26 issubstantially neutral and its armature immediately retracts, ungroundingthe starting-wiper 27. During the secondary travel of line selectorEunder the influence of relay SR, the neutralizing circuit through theright winding of relay 26 is continued closed at armature 77 of relaySR. When the line selector E has completed its selection, the opening ofcontact '7 7 to deenergize the right windlng of relay 26, and theopening of contact 21 to de energize the left winding thereof, willoccur nearly simultaneously and the armature of said relay may remainunattracted, or it may momentarily attract.

on the first step of selector E, the closure .of contact 62 causes aflow of current over contacts, relay R will remain operated and acontact set 28, 31*, the relay the magnet MM will continue to drive theswitch wipers. If the neutralizing of the core of relay 26 fails tooccurrsoon' enough to unground the Wiper 27 before the masterswitchwipers make their first ste to engage will continue operated and themaster-switch wipers will engage the nextcontact set 28,31; and if thiscontact set is that of an idle line selector, the master-switchwill cometo rest, since relay R will become deenergized, its circuit being openedat contact 62 of the idle line selector, and the wipers of the mas-.ter-switch Mfwill rest engaging contacts of such line selector,'ready tostart the same. Should it by chance happen that the opening 8 of contact.21 and that of contact 77 occur,

one long enough after the other to cause the {momentary attraction ofthe armature of the relay 26, and if the wipers have come to restengaging 'a contact set 28, 31, the only effect will be to initiate'astepping forward of the said wipers to engage the next pen that, shouldthe armature of relay 26 momentarily attract, circuit will be closedthrough the relay R too short a time to permit of a step of themaster-switch wipers. It will be understood that by adjusting thevarious relays involved, the openings of con tacts 77 and 21 can becaused tooccur so close together that the armature of relay 26will notattract when a line is selected. The present arrangement avoids thenecessity of very close adjustment in this regard.

As soon as line'selector E initiated. sec ondary travel, the attractionof armature 80 of relay SR closed a circuit through contact 71, theresistance 1", contact 60-55, wire 50, through the right'windin'g ofrelay 23-t0 battery B. The windings of relay 23 being now opposed andthe resistances 1* and 1" being so proportioned that said windings nowsubstantially neutralize the core of the relay 23, its armature isretracted, so that on the secondary travel of the line selector,

the multiple group contacts 54 are unselectable; By this arrangement,should two line selectors .be started and reach their groupcontacts 54of the same group, one immediately after the other, only one of themwill move its wipers into that sub-group of line contacts, unless indeedthere betwo calling lines in said, sub-group. In such case, the

inclusion of one resistance r in circuit with the right winding of relay23 will not deenergize said relay, since the fact that two lines arecalling, which have contact sets in: will have caused the inclusion of acall before a first calling line has been se-.

lected by a line selector, the initiation of the second callwill causethe re-operation of the master-switch relay 26 to cause it to start an-It will also, beob served that if a second calling line initiates Iother line selector, since the operation of the second line relay willinclude its winding in a branch of the circuit of the left winding ofrelay 26 and greater current will flow in dial 7 so thabthe same is nowoperable by hand. To transmit the called number 2345, subscriber C'first rotates dial 7 clockwise until two insulating teeth are below thespring 3, and then replaces it, whereupon the dial is spr1ng-restored ina reverse clockwise direction, the two teeth causing two 'momen tarybreaks at contact 3, whereafter a tooth at the extreme left of dial -7causes one momentary break at contact 4. A stud 8 is mounted on the dialso that when the dial is in other than normal position, the stud ismoved free of the spring 5 and the springs 5, 6 are by their tensionconnected together and to ground. The springs 3, 4 are therefore bothgrounded as long as the dial is off normal; and while two openings arebeing produced at contact 3, each of which will deenergize momentarilyrelay PR, the relay SR will remain operated by current over limb S andthrough contacts 4, 6 to ground. Conversely, when contact 4 is opened asbefore described, it will denergize the relay SR, but the contact 3 willbe closed and the relay PR will remain energizedby current over limb Pand through contacts 3 and 5-0 to ground.

The two deenergizations of relay PR transmit two current impulses fromground through contacts 91, 88, 99, magnet PM to battery, and twoprimary steps of first selector F are caused, the wipers 110, 111 and112 being adjusted adjacent to the second group of second selectorcontacts, terminals of second selectors assigned to the second thousand.On the subsequent deenergiza-' tion of relay SR5, a current impulse istrans mitted from ground through contact 89, normal contact 92, fcontact100,'contact 102 of the primary off-normal switch which was closed onthe first primary step, and through.

relay BR to battery, operating-said relay whose armature 107 connectsits winding through normal contact 104 with the private wiper 110.Armature 108 closes a circuit for alternating current through secondarymagnet SM and said magnet steps the wipers 110, 111, 112 step. by stepto engage successive contact sets of the selected group.

Until that of an idle second selector is reached, the wiper 110 willengage successive'ly grounded contacts 113" and. the relay BR willremain energized. As soon, however, as the wiper 110 engages the contact113 of an idle secondselector, such contact will be disconnected fromground and'relay BR will deenergize, theopening of contact 108preventing further actuations of magnet SM so that the wipers of switchF will remain engaging the contacts of the selected second selector.The'clo'sin of normal contact 107 will have connecte' ground throughwiper 110 to the contacts 113 thus selected, rendering them busy. Thesecondary offnormal contacts 99, 100 were shifted on the first secondarystep of-the first selector F so that magnets PM and BR were discon-' to'2399. The. following deenergization of relay SR transmits a currentimpulse from ground, through contact 89, normal contact 92, contacts109, 112-115, 102 and relay BR and said relay initiates and controlssecondary travel of second selector H to select contacts of an idleconnector in thesame manner that relay BR controls the travel of firstselector F, the detail of operation of second selector H bein apparentfrom that given for the first se ector, like parts at H and F beinggiven like reference characters with different exponents.

leases it. Four resulting denergizations of relay PR transmit fourcurrent impulses through contacts 111-114,1l1 ,-117, 1.21 and magnet PMto battery, causingfour actuations of said magnet and four primary,

steps of the, wipers'141, 142, 143, to select the fourth group of calledline contact sets 9, 10, 11, comprising contacts of lines 2341 to 2349inclusive, followed by those of line 2340, zero being ten impulses. Afollowing deenergization of relay SR will transmit a current impulsethrough contacts 112-115, 112 -118, normal contact 122, secondary magnetSM to battery, which magnet will cause one secondary step of the wipers141,

142, 143, toward the edge of the contact bank, but said wipers do not,at the conclusion of this step, engage the first contact set of the'group, since the normalposition of the wipers of a connector, aftertheir rim-ary adjustment, is always two secondary steps distant from thefirst contact set of the selected" group. By this first step, however,

Sub-" scriberC now actuates his dial until four teeth are brought belowspring 3, and re' tion shown, connected to the active side of thesecondary off-normal contacts 121, 122

are shifted,121 to engage its alternate contact, while 122 is shiftedsufficiently, to

disengage its normal contact, but not to en- 7 "gage its alternatecontact, the latter occurring only on the second'se'condary step of theconnector. The calling subscriber. C now actuates his dial until fiveteeth are brought below spring '3, and releases it.

Thereafter a deenergiz'ation of relay SR transmits a current impulseover the beforetraced path through contact 118, thencethroughalternatecontact 122, normal contact 128 and lower windin of test relayTR'tobattery B. Relay LOR, said relay, by'armature 127, locking to ground at124. The test relay TR'n'ow proceeds to test the called line, and ifsaid line be found idle, the ringing generator.

ill

will be connected to the called line to si thesubstation. If the line bebusy, the ringing generator will remain excluded and thebusy'interrupter I will be connected with the calling line, at whosesubstation the sub- 'scriber will hear thebusy signal and will rciplacehis receiver to disconnect the central ce apparatus.

Assuming first the called line to" beidle, its multiple contacts 9willbe in the condibatteryB through contact 15 of relay LE andwinding12. The engaging wiper 141 is, .011 the attraction of armature 133' ofrelay TR, also connected to the activeside of the of armature 128 ofrelay LOR opens the cir- 'cuit of the lower windm of the relay TR,

said relay deener izes, since the two ends of its upper win ing areconnected" to the active side of battery B and said relay TR denergizesLAs soon as this occurs, a circuit is completed from ground through ringing control relay RCR, contacts 126, 133, 141--9, 15, winding12 of relayCO of the called line to battery B and relays CO and RCR both operate,the ormer, by its armature 20, connecting the ground through relay RCRto the priyate contacts 51 of the called line at the line selectors, sorendering them busy. The interrupter I, a constantly rotating device,will now alternately energize and deenergize the generator relay GR,whose armature 140 alternately connects and disconnects the ringinggenerator with and from the called line, causing. its substation Roperates and itsarmature 134 actuates the locking relay,

battery,B 'Thus as soon as the attraction bell to periodically sound inthe well-known I manner. When the called subscriber removes h1sreceiver, hook-lever 1 closes a conductive circuit through thesubstation; and f as soon as armature 140'is retracted, a cir-' cuit iscompleted as follows: from the'active side of battery A, throughanswering relay 7 AR, contact 129, normal contact'140, con tact 142-10,limb P, contact 3, the trans mitter and upper hook-switch cont-acts, im-

pedance 2, contact'4, limbs, contact 11 143, inductive resistance IR,attracted arma ture 130, t'o battery B. This flow of current energizesthe transmitter at substation 'C for talking andoperates relay AR, whosearmature 135 actuates closing} relay 'CR' which, by armature 137, locksto ground at contact 124. Armature 138 opens the circuit of relay GR sothat it remains de'ner-- ized' .rin' in current, accordin l 'remain-- 7111g exciu ed from the called line. Anna tures 136 and 139 complete thetalking circuit at theconn actor and the two subscribers are now inconversation over a circuit traced from substation C and over, theheavily marked conductors to substation C, the

calling and called portions of the talking circuit being unitedinductively by the condensers at F. I a r It will be seen that when thecalled subscriber answers and contacts 136, 139are closed, positivebattery at A is, over the 112", 115112, and alternate contact'92 andrelay RRT with the negative battery B so thatthe relay RR .is heldenergized during conversation by current passing over the called line.On the operation of relay RR, its armature 97 energizes locking relayLOR" which, by armature 93, looks to ground at 101 andover wire 82, toground As before stated, when either subscriber replaces his receiver,all the central ofiice switches are restored to normal. Assuming thatsubscriber C replaces his first, the opening of alternate contacts at 1will deenergize, simultaneously for the first time, relaysPRf and SR andarmatures 87 and 90 are simultaneously retracted to close the releasecirk cuit 83. Current will then flow from ground through release relayRR? at F, -contacts 90,

relay RR at E, to battery B and both said relays energize. 'RelayRR-atE, by armature 69, actuates release magnet RM by current throughcontacts 61 and 65 and said magnet withdraws the lreta'i'ning pawls ofline selector E and its wipers and. off-normal called subseriberfs'line, connected over a return circuit traced through contacts 11 8 .87,wire 83, contact 73, lower winding of contact's are automaticallyrestored to norma l. Relay RR, by armature 69, has locked to R and untilthe wipers are fully restored, at which time the primary off-normal POound inparallel with release magnet ated. During restoration, thetalking wipers 57, 58 are held on open circuit, since armature 7 Omaintains relay SR operated until the wipers are free of the contactbank, as hereafter explained.

Relay BB at F, by armature 103, locks itself in series with relay BR,and magnet RM is energized by current from ground through contact 108,alternate contact 105, and the winding of said magnet to' battery, themagnet being then effective to withdraw the retaining paw-ls of firstselector F, whose wipers will be automatically restored, at

which time the opening of primary off-normal contact 102 deenergizesrelays BB and BB". Before magnet RM can attract its armature, however, acurrent impulse will pass from battery B through alternate contact 1'04,contact 110-*113, contact 101 release relay KB of second selector H,which relay, by armature 103*, looks in series with busy relay BBCurrent will then flow from ground through alternate contacts 108*,105', release magnet RM to battery, and said magnet withdraws theretaining pawls of second selector H, causing its wipers to be restoredto normal, at which time the opening of contact 101 will 'deenergizerelays BB and BB Before magnet RM can attract its armature, however, animpulse of current flows from .fbattery B through alternate contact 104,contact 1 10*- 116, 119, release relay RR to ground, which relay, byarmature 123,1ocks itself and, by

armature 124,. actuates release magnetRM which withdraws the retainingpawls of connector K, whose wipers 141, 142, 143

thereupon restore to normal, at which time the opening 'of contact 120of course de-" energizes the release relay RR. It will be observed thatzon the attraction of armature 124, the circuitsofyrelays LOB and CR areopened and said relays deenergi'ze. Al-

though thew-ipers 141, 142-, 143 have now been restored to normal andaccordingly disconnected frointhe contacts 9, 10, 11, and

tive side of battery A, through winding 13,

alternate contact 18, limb P, to the raised hook-lever v1, returningover limb S, alter nate contact 22, and through winding 14 to the activeside of battery B. v The line relay LR can accordingly not be energized.When the called subscriber C replaces his .receiver, the openingof aconductive circuit at the substation de'energizes windings 13, 14, thearmaturesof relay CO retract, 'and should the subscriber now remove hisreciver, his line relay LR will operate and cause his line to beselected by a line see-- lector.

lVere the called subscriber C to replace his receiver before the callingsubscriber C, the opening of the conductive circuit at substation C willdeenergize answering relay AR at K and relay'RR at F. On thedeenergization of the latter relay, circuit is completed as follows:from ground throughrelease relay EH closed contact 94, normal contact96, attracted armature. 95 and over wire 83 and cont-act 73, lowerWinding of release relay RR to battery B The energization .of theserelays causes the restoration to normal of all the central otficeapparatus in the way just described. If it be assumed that thesubscriber C still has his receiver removed, his relay 00 will remainoperated, although line selector E has been disconnected therefrom,because of the circuit through the locking windings 13 and 14, tracedthrough alternate contacts 18 and 22.

Let it now be assumed that at the time the connector K made connectionwith the called line, said line was busy. In such case, the privatecontacts 9 would be grounded. in one of the several Ways heretoforementioned;

and on its initial operation, the relay TR would be locked by currentflowing from battery B through the upper winding of said relay,alternate contact 133, contact.

141'-9, and to ground. Busy interrupter I would remain connected to theupper talking conductor at connector K and the calling subscriber Cwould hear the busy signal in his receiver. He would accord i 1. re lacehis receiver, deener izing relii y s Plt and SR and the central olficeapparatus would all be restored-to normal.

Returning now to the master-switches M and M, let it be assumed that theidle line selector, for which the relay 26 closed a starting circuit,failed to operate and start to select the calling line. In such case,the contact 63 would remain open and current flowing from ground a thealternate contact, the release of contact 37, linked to 35, beingsimultaneously shifted to engage its alternate contact. On the closureof alternate contact 35, the bell 36 will sound to advise the centralofiice attendant that the master-switch M is in trouble,

operatively associate the=circuits of master" switch M with the commonconductor 25 extending to, the line relays, a-nd with the Suppose theline selector E starts and for,

some reason sticks at some point in its operation without completing itsselection; it will be obvious that current will continue to flow throughboth windings of relay 26 and the heat-coil 72,, will blow and in thiscase also cause the connection in circuit of the I substitutemaster-switch and of the alarm bell. Furthermore, should therelay R getout of order or have its circuit closed with the result that itsari'nature stayed continuously attracted, thus causing magnet MM tocontinuously rotate the wipers 27 and 30, the generator impulses will,after a certain length of time, blow the heat-coil h,

at which time alternate contacts 32 and 34 will automatically close, theclosing of 32 causing the bell 33 to sound, while the cloi sure of 34energizes the relay 88 which operatively connects in circuit thesubstitute master-switch M. i It will of course be the duty of theattendant, as soon as either bell sounds, to ascertain the trouble asspeedily as possible and replace the blown heat-coil with a new one,thus again cutting into circuit the regular-service master-switch M. Themaster-switchM has heat-coils h and h similar to the coils h and 71, ofM, so that if, what would be a very rare occurrence,

both master-switches should be disabled, the fact would be atonceadvertised to the central oflice attendant. It will be observed thatthe wire connected to the wiper 30 of master-switch M is connected toalternate contacts 37 and 34 so that, if the heat-coil were to blow, thecontact of the line selector engaged by wiper 30 will be rendered busybefore the wiper 30*. Thus a disabled line selector, or a contact onwhich the disabled master-switch M rests, will be incapable of selectionby the alternate master-switch when it is cut into circuit.

Referring to the mechanical drawings,

Figs. 2 to 6, the one hundredcontact sets 51,

52, 53, which comprise the main switch bank, are arranged in tenvertically extending groups of ten contact setseach, being mountedbefore the wipers 56, 57, '58,'as shown in Fig. 3,'as if extendingthrough the inner surface of a section of a hollow sphere. Said wipers56, 57, 58- are given their primary' adjustment, by being rotated stepby step from left to right beneath the lower edge of the contact bank asviewed in Fig. 3, eachstep bringing them beneath a different group ofcontact sets. Their secondary adjustment is effected by moving the wiperends. adjacent tothe bank upward, each secondary step causing them toengage a different contact set. As shown in Fig. 2, the

wipers are supported by a primary shaft PS and extend throughsaid shaft,being pivoted at 209. The rearward extending portion of the wipermounting is provided. with a bearing engaging the slotted wheel members210, free to rotate in the bearing. Engaging the slots, is an angularpiece 208 fastened to secondary shaft SS and sufiiciently broad so thatit remains .in engagement with the slots after any primary adjustment ofthe wipers.

,The group contacts 54:,- 55 are mounted be- .low the contact bank andtheir associated group wipers 59 and 60 are rigidly fastened .to theprimary shaft PS and partake only of the primary movements of theswitch.

For rotating the shaft PS and thus effecting the primary adjustmentsof'the wipers, a

primary ratchet 225 is rigidly attached to the shaft PS, as shown inFig. 6. The'driving pawl 202, adapted for actuation by the armature ofprimary magnet PM, is arranged on successive actuations to engagesuccessive teeth of the ratchet 225' and so drive the ratchet, theprimary shaft, and

the wipers 56 to 60, inclusive, rotarily step by step. The primaryadjustment of the switch is effected against the tension of the spring213 shown in Fig. 4; and to prevent back movement, the primary retainingpawl 203 is provided. After the primaryad ustment is completed,actuations of secondary magnet SM will effect successive thrusts of itsarmature controlled pawl 206, which, en gaging successive teeth of anassociated ratchet cut in secondary shaft SS, drives said shaft downwardstep by step, the sec-' ondary retaining pawl 205 holding the shaft SSagainst back movement after each step, which would otherwise occur underthe in fluence of the spring 214 linked to the secondary shaft SS by thelever 215,, whose long arm loosely engages a screw inserted in the shaftSS. Each downward step of shaft SS moves the piece 208 a step downwardand the contact ends of the wipers 56, 57,

58 are moved upward to engage successive contact sets of the selectedgroup.

In Fig.5, the piece 200 is shown fastened to the shaft PS and carrying astud 201, which normally engages an angular extension of the primaryoff-normal spring 64, to

which the other s rin s 61, 62, 63 are linked by insulating stu s. n thefirst-rotary step of shaft PS, the stud 201 frees the spring 64 and theprimary off -normal springs are moved by their tension to theiralternate positions. As shown in Fig. 4, an angular piece 211,.normallyholds in its raised position an insulating s acer connected to thesecondary ofi-norma springs 73, 74, 75. A

piece 212, fastened to secondary shaft SS, normally holds the arm 211,which extends parallel with shaft SS, in its raised position. ()n thefirstdownward step of shaft SS, the piecev 212 clears the piece 211,which then drops down, allowing the springs 73, 74. 75 to be moved bytheir tension to their alternate positions. with a tooth 226, adaptedwhen the piece 211 drops down, as described, to engage any adjacenttooth of the primary ratchet 225 to render ineffective the tension ofthespring 213 while the secondary shaft SS is being restored to normal,as hereafter described.

" To restore the described mechanism to normal, it is only necessary toenergize the release magnet RM, whose armature 204 then engages arearwardly extending por-' tion of the primary retaining pawl 203 andengagement with the tooth of the primarv rotates said pawl'to free theprimary ratchet 225. The pawl 208 has a projection 207 interlocking withthe secondary retaining pawl 205, so that the described movement of theprimary retaining pawl 203 serves to also withdraw the secondaryretaining pawl. Thereupon the spring 214; is effective to raise theshaft SS upward until the piece2l2 raises the piece 211, whereby thesecondary off-normal contacts are restored, and abuts upon the lowersurfaceof the switch frame. Until this occurs, the tooth 226 remains inratchet 225. WVhen the secondary shaft reaches normal, however, at whichtime the wipers are below the lower edge of the contact bank,the tooth226 disengage-s ratchet 225 and the spring 213 is effective to rotatetheprimary shaft and the wipers of the switchsback to normal, atwhichtime the stud 201 (Fig. 5) restores the primary off- .normal contacts.

The switch. justdescribed, which is specif ically arranged to performthe functions of line selector E, may also serve for first 'selector F,second selector H, and connector K. For these latter uses, however, thegroup contacts and group wipers are not. required; and in thecase of theconnector, the wipers will be so adj ustcd with respect to the loweredge of the contact bank as to be two steps distant from the firstcontact set of the selected group after the primary adjustment iscompleted, as already referred to in connection with the circuits.

The various battery symbols, shown as havingthc same pole grounded, maybe asingle source of current if preferred, and

the variousgenerator symbols, shown in systems other than those of-thespecific char actor herein described, and the appended The piece211 isprovided claims are intended to be of scope sufficient 1 responsive tocurrent over-any of said lines,

of a second like circuit and a'switch auto- .matically operatedresponsive to trouble in said organization to substitute said secondcircuit for said first-mentioned circuit in said organization. I

2. In a telephone system, the combination with an organizationcomprising telephone lines, selectors, a starting circuit operableresponsive to current over said lines and mechanism sensitive to theelectrical condition of said circuit to connect said selectorsinterchangeably with said lines, of a second starting circuit, and aswitch automatically operated responsive to trouble in said organizationto substitute said second circuit for said first-mentioned circuit in.said organization. I 3. In a telephone system, the combination withselectors and means for starting the paratus responsive to an abnormalcondition of said means for automatically connecting said secondconductor into operative relation with said selectors.

5. In "a telephone system, the combination with selectors, of aconductor for distributively starting the same and operativelyassociated therewith, a second conductor for distributively startingsaid selectors and inoperatively associated therewith, means foraltering the electrical condition of said first conductor in order tostart a connected selector,. and an automatic switch operated responsiveto failure of said connected so lector to start to operativelydissociate said first-conductor from said selectors and operativelyassociate said second conductor therewith. a

,6. In a telephone system, the combination with selectors, of aconductori for distribut-iv ely starting .the sameand operativelyassociated therewith, a second conductor for distributively startingsaid selectors and inoperatively associated therewith, means foraltering the electrical condition of said first conductorin order tostart a connected selector, .and means responsive'to a failure ofsaidconnected selector to properly perform its functions serving tooperatively dissociate said first conductor from said selectors andoperatively associate said second c'onductor therewith. v

7. A telephone organization including telephone lines, line selectors toselect said lines,'a master-switch common to said selectors and linesoperable responsive'to current over a line to start an idle selector, asecond master-switch, and automatic means responsive to trouble in saidorganlzation to substitute saidsecond master-switch for saidfirstswitch.

8. A telephone organization including telephone lines, line selectors'toselect said lines, a master-switch common to said selectors and linesoperable responsive to current over a line to start anidle selector, asecond master-switch, a relay associated with the first master-switchadapted to initiate travel of a line selector, and means responsive toan abnormally prolonged How of current through said relay to operativelyconnect said second master-switch in circuit.

9. A telephone organization including telephone lines, line selectors'to select said lines, a master-switchcommon to said select- .ors andlines operable responsive to current over a. line to start an idleselector, a second master-switch, a mag-net for adjusting said firstmaster-switch, and means automatically operated responsive to abnormallyI prolonged actuation of said magnet 'to operatively connect said secondmaster-switch in circuit. 1 v

10. Ina telephone system, the combination with an organizationcomprising telephone lines and a circuit adapted to be in-- fluencedresponsive to current over a line, of a second like circuit, aheat-controlledcontact, and means responsive to a prolonged flowofcui'rent to change the connection of said contact to substitute saidsecond circuit for said first-mentioned circuit in said organization.

11. A telephone system including telephone lines, selectors, a startingcircuit operable responsive to'current over a line to initiate travel ofa selector to selectsaid line, a second starting circuit and aheatcontrolled contact automatically operatedresponsive to thepresenceof trouble to operatively connect into circuit said secondcircuit.

12. In a telephone sfystem, the combination with SBlBCtOI'SyRO astarting circuit operatively associated with saidselectors, a 1 secondstarting c1rcuit,and;a heat-controlled contact actuated responsive todisabling of the first starting circuit to automatically connect intooperative relation with-said selectors said second starting circuit.

13. I m a telephonesystem, the 'combina-' tion with selectors, ofa'comluctor for start- 'du'ctor with said selectors.

ing the same, means for interchangeably associating said conductor withdifferent selectors, a second starting-conductor not in prolongedcurrent How, and a switch automatically operated by the changing of theconnections of said contact to connect said second conductor tooperative relation with said selectors.

14. A telephone system including selectors, means for distributivelystarting said selectors, a second means for starting said selectorsnormally in inoperative relation therewith, apparatus for causing acurrent flow in said first means for the purpose of starting a connectedselector, said current flow continuing upon failure of said connectedselector to start, a heat-controlled contact adapted to be actuatedresponsive to an abnormally prolonged continuation of said current flow,said contact serving when actuated to operatively associate said secondmeans with said selectors.

15. A telephone system including selectors, a conductor fordistributively starting the same and operatively associated therewith, asecond conductor for distr'ibutively. starting said selectors andlnoperatively associated therewith, means for. causing a current flowover said first conductor for the purposeof starting a connectedselector, a-

heatcontrolled contact, means for actuating said contact responsive toan abnormal continuation of said current flow due to a failure of saidconnected selector to properly p erform its functions, and switchconnections controlled by the actuation of said contact serving tooperatively dissociate said first conductor from said selectors andoperatively associate said'second conductor therewith.

16. Atelephone'system including selectors,

trolled contact, means for actuating saidcontact responsive to anabnormal continuation of said current'fiow due to a failure of saidconnected selector to properly perform its functions, an electromagnetadapted to ha ve its electrical condition changed respons ve to theactuation of said contact, ,and contacts controlled by said magnetshifted 5 p responsive to a change in its electrical condi. tion tooperatively associate said second con- 17.- In atelephone system, thecombination with terminal contacts. arranged in groups, a selector forselecting a group and then a contact of the group, a common or groupcontact for each said group, means for altering the electrical conditionof a groupcontact to cause selection of its group by a selector, andmeans responsive to initial travel of the selector to select a contactot the selected group to render the group contact unselectable.

18. la a telephone systein,the combination with terminal cont-actsarranged in groups, a selector for selecting a group and then a contactof the group, a common or group contact for each said group, meansi oraltering the electrical condition of a group contact to cause selectionof its group by a selector, and apparatus actuated by the selector oninitiation of its travel over contacts of the selected group to renderthe group contact again unselectable.

it). In a telephone systenntlic combination with terminal contactsarranged in groups, a selector for selecting av group and then acontact. of the group, contact for each said group, means foraltering=the electrical character of an individual contact, means foraltering thc electrical character of the respective group contact, andmeans controlled by an operated selector for first restoring the electri-al character of the group contact and then the electrical character ofthe individual contact.

20. In a telephone system, the combination with terminal contactsarranged in groups,

a selector for selecting a group and then a,

contact of the group, a common or group contact for each said group,means for alter-.

ing the electrical character of an individual contact, means foraltering the electrical character of the respective group contact,

means controlled by an operated selector for first restoring theelectrical character of the group contact and then the electricalcharacter of the individualcontact, and means rendering the selectorineffective to restore the electrical condition of'the group contactwhenmore than one individual contact of the same, group have theirelectrical characters altered.

21. In a telephone system, the combination with normally unselectableindividual terminal contacts arranged in groups, select ing mechanismsforselecting a group and then a contact of the group, a common or groupcontact for each said group, said group contacts being also normally"unselectable means for each individual contact e c for rendering itselectable, said means also bein ada )ted to render the res )ectivegroup contact selectable, and apparatus operated b a selectin mechanismfor rendering the group contact unselectable- .and

thereafter the associated individual. cont-act.

22. In a telephone system, the combination with normallyunselectahleindividual terminal contacts arranged in groups. se

a common or group lecting mechanisms for-selecting a groupand then acontact ofthe group, a common f or group contactfor each said group,said. roup contacts being also normally unseiec'iable, m ans for eachiiulividual contact tor rendering it selectable, said n'ieans also beingadapted to render the respective group contact selectable, apparatusoperated by a selecting mechanism for rendering the group contactunselectable and thereafter the associated individual contact, and apparatus etl'ective by the operation'o't the means of a second individualcontact of the same group to render inetfective the operation of saidfirst-mentioned apparatus.

23. A. telephone system inclui'ling a tele;

phone line, selective mechanism to select said line, a starting circuitresponsive to current over the line to initiate travel of said mechanismto select said line, means independent of said lines circuit for,disconnecting said mechai'iism from said line, and apparatus includinga relay held energized by current over said line to prevent reoperationof the starting circuit on disconnection.

A telephone system including a telephone line having multiple terminals,se-

lective mechanism to selectsaid terminals, means tor altering the normalelectrical. condition of said contacts to render them solectable by saidmechanism, means ctlective by connection of said mechanism with saidterminals to render them uuselectable, apparatus independent of saidtelephone line to disconnect said mechanism from said terminals, andmeans controlled by current flowing over said telephone line serving tocontinue said contacts unselectable after disconnection of saidmechanism.

27. A telephone system including a telephone line, an electromagnetindividual to said line, link-circuits, automatic mechanism forinterchangeably connecting said line with an idle link-circuit, andmeans controlled by said mechanism in its operation to include awindingof said magnet and said telephone line in circuit.

26. A telephone system including a telephone line, link-circuits, meansnormally adapted for operation responsive to currents over said line toautomatically cause connection of an idle link-circuit to said line, acut-off relay coi'iperating with said means, a circuit for operatingsaid cut-otl' relay on connection of a link-circuit with said line, anda contact controlled by said cut-oft relay when energized to connect.its winding with said line to hold said relayenergized by current oversaid line after said link-circuit is disconnected theri-zfroin.

v27. A telephone system including tele phone lines, line selectors forselecting said lines, a line relay normally.conti'olla'bleresponsive tocurrent over a telephone line to initiate travel of a line selector toselect the said line relay disconnected while ourrent .line, a cut-01frelay serving to deenergize flows in saidtelephone line. 10

said line relay on selection of said line, In witness whereof, Ihereunto subscribe means for initially energizing said cut-ofi' my namethis 6th day of January, 1909. relay over a local 'circuit and thereuponALFRED H. DYSON.

locking said relay over said telephone line Witnessesz whereby,aftGPClISCOIIIIBCtIOD of said selector THO AS H. FEReUsoN,

from said line, said cut-ofl' relay maintains CAROLYN WEBER.

